Effervescence is a widely used, desirable and useful property of many commercial products. Notable among these are carbonated soft drinks, stomach distress medications in the form of pills or powders which are added to water immediately before consumption, soft drink tablets or powders which effervesce upon dissolving in water, quick dissolving pills, tablets, denture cleansers, etc. Virtually all effervescing products intended for consumer use are based on the evolution of the gas, carbon dioxide. Others are based on the evolution of oxygen as from perborates, peroxides and the like.
In liquid products such as carbonated beverages, the carbon dioxide is dissolved in the water of the beverage under pressure prior to bottling, canning, or mixing with flavored syrup as in a conventional soda fountain. Sufficient pressure is maintained on the carbon dixoide solution to retain that gas in solution until the product is ready to be used. When the bottle or other container is opened or the liquid is discharged from a pressurized, soda-water siphon bottle or from a pressurized storage tank in a soda fountain, the aqueous solution of carbon dioxide immediately becomes supersaturated at atmospheric pressure and some of the dissolved carbon dioxide begins to come out of solution in the form of tiny bubbles of gas which are released continuously and for an extended period of time.
Most effervescent solid products such as powders and tablets, are prepared by incorporating therein suitable quantities of reactive ingredients, namely, an acidic material and a carbonate such as sodium bicarbonate. As long as the resulting mixture (e.g., tablet) remains dry, these reactive ingredients do not produce any significant amount of carbon dioxide. However, when the products are added to water, both reactive ingredients dissolve and are thus enabled to react with each other creating a desired amount of evolution of carbon dioxide gas, one of the end products of the reaction. Generally, this reaction proceeds rapidly so that the acidic and alkaline ingredients are neutralized and the effervescence essentially stops, although there may be a slow release of carbon dioxide which has dissolved to a minor extent in the water during the vigorous evolution phase. Normally, however, the effervescence does not continue nearly as long as the effervescence created by dissolving carbon dioxide in water under pressure. This is because the carbon dioxide created by the reaction of acidic constituents and sodium bicarbonate does not dissolve to any great extent in the water, since the entire system is usually at atmospheric pressure during the time the gas is being generated and is bubbling through the aqueous medium. Hence, the carbon dioxide merely passes through the liquid and effervescence ceases almost completely as soon as the generation of gas by chemical reaction is complete.
It can be seen from the foregoing that the application of effervescent properties to various types of products is generally limited to situations where dissolved gases may be allowed to be released from the solutions in which they have previously been dissolved or where gases may be created by chemical reaction during or immediately preceeding the time of use of these products.
The present invention is predicated upon a different principle for the purpose of creating a vigorous, relatively long-lasting, auditory effervescence in a wide variety of types of products. It has been found that certain compounds, liquefied gases, which are immiscible with a matrix can be retained essentially completely in the liquid phase with only a slow boiling occurring at temperatures which are significantly higher than the boiling point of these liquids at the prevailing environmental pressure.
Liquefied gases, such as fluorinated hydrocarbons are commonly used as propellants for various types of aerosol products such as paints, insecticides, waxes, whipped toppings for foods, and many other types of end products, which are retained in aerosol containers. When the pressure is released by means of a valve on the aerosol container, the contents of the pressurized container are discharged and any liquefied gas propellant which is discharged from the container vaporizes essentially instantaneously as the contents of the container enter the much lower pressure zone (atmospheric pressure) outside of the container. Frequently, liquefied gas propellants are combined with dissolved gas propellants and these dissolved propellants also tend to vaporize instantaneously upon release fom the pressurized container and combinations of the formerly liquefied gas and the dissolved gas create bubbles or foam in the product as discharged. This type of product is exemplified by shaving creams and whipped toppings. Little or no liquefied gas is retained in the dispensed product, thus the product is characterized by little or no effervescence.
There are many products described in patents and in technical literature which describe the use of liquefied gases as propellants for products contained in aerosol containers. Frequently, these liquefied gases not only propel the product from the container but some of the liquefied gas emerges with the product from the container and serves the further purpose of creating a foam by vaporizing essentially instantaneously as the pressure is released upon leaving the container. Sometimes the liquefied gas is used as a dispersant for other liquids after the product leaves the aerosol container as in the case with insecticide sprays, deodorant sprays, or the like. In this instance also, the liquefied gas performs its function by vaporizing essentially instantaneously as the product leaves the aerosol container and the internal pressure is released. In still another conventional use of liquefied gases, substances such as medicaments, antiperspirants, waxes, etc. may be dissolved in the liquefied gas within the aerosol container. When these products are discharged from the container, the propellant is intended to vaporize essentially instantaneously, depositing a film or a dusting of the previously dissolved active ingredient upon the surface to which the stream or spray is directed. Hair sprays or lacquers are also typical examples of this type of use of a liquified propellant. Still another common use of liquefied gas propellants is to serve as a means of discharging dry, insoluble materials such as talc or lubricating powders like graphite from an aerosol container. In these instances the dry material is shaken with the liquid propellant in the container immediately before discharge, the dry ingredient thereupon being dispersed and leaving the container in the stream of liquefied gas as a dispersing solid. Upon emerging from the container the liquefied gas vaporizes essentially instantaneously, depositing a thin film or dusting of the dry material upon any surface toward which the stream or spray is directed.
Accordingly, there has been no previous description of the use of a liquefied gas, not only to propel the contents of an aerosol container out of that container but also wherein some of the liquefied gas is dispersed throughout the aqueous or alcoholic matrix of the contents of the can and serves as a source of vigorous bubbling and effervescence in the products which are produced by so discharging some of the can contents into a vessel, on a surface, or into other liquids in a vessel. No previously described products, at the time of use, comprise liquid matrices containing dispersed therethrough or at the bottom thereof substantial quantities of liquefied gases which exist as liquids boiling slowly and continuously for long periods of time (one-half hour up to 24 hours or longer) at atmospheric pressure and at temperatures which may be as much as 100.degree. F. above the expected boiling point of said liquefied gases.